This product is a set of electric-mechanical transformation, together with proportional control amplifier, used in the electro hydraulic proportional system of DC 24V. They are used in the proportional flux control valve and proportional directional valve of REXROTH. In the range of the rated stroke and rated current, the input force & stroke is proportional to the input current, the force is permanent within rated stroke, the input current is infinitely variable control within rated range. It can make the outfit of the hydraulic system realize infinite speed variation, commutation and telecontrol.